The story first broke in 2008, and initial transplant results were published in the New England Journal of Medicine. Brown was treated for leukemia with an adult stem cell transplant, which is becoming a standard treatment. But the doctors, knowing that Brown had AIDS, used specific adult stem cells from a donor selected because the donor's cells lacked a key protein, CCR5, that the AIDS virus must bind to infect a cell. Not only did Brown recover from his leukemia, but the AIDS virus seemed to disappear from his system.